There have recently been found in the central nervous system specific binding sites for compounds having an imidazoline structure (P. Bousquet et al., Biochem. Pharmacol., 1983, 32, 1459; J. Pharmacol. Exp. Ther., 1984, 230, 232), different from histamine receptors (P. Ernsberger et al. Soc. Neurosci. Abstr., 1986, 12, 1334). Those receptors have been characterised at the level of the nucleus reticularis lateralis, in the rotroventral portion of the medulla oblongata (G. Brica et al., Eur. J. Pharmacol., 1989, 162, 1), are distributed heterogeneously in the brain (P. Ernsberger et al., J. Pharmacol. Exp. Ther., 1990, 253, 408), and are also present at the peripheral level (P. Ernsberger et al., Am. J. Hypertens., 1990, 3, 90; J. E. Piletz et al., Biochem. Pharmacol., 1991, 42, 346). Two receptor sub-types, I.sub.1 and I.sub.2, have been identified (M. C. Michel et al., Trends Pharmacol. Sci., 1992, 13, 369) according to their ability to bind clonidine (sub-type I.sub.1) and idazoxan (sub-type I.sub.2).
Those receptors appear to be strongly implicated, together with .alpha..sub.2 -adrenoreceptors, in the vasodepressive and anti-hypertensive action of certain compounds such as clonidine and rilmenidine (G. Brica et al. Eur. J. Pharmacol., 1989, 162, 1; R. E. Gomez et al. Eur. J. Pharmacol., 1991, 195, 181). Their role in stimulating the release of insulin by the .beta. cells of the pancreas has also been demonstrated (Schutz et al., Naunyn-Schniedeberg's Arch. Pharmacol., 1989, 340 (6/712). It has also been shown that imidazoline receptor ligands can be especially valuable in the treatment of psychiatric and neurological disorder (D. S. Nutt et al., Annals New York Academy of Sciences. 1995, 125). The compounds of the invention have a novel structure which surprisingly provides them with very great affinity for imidazoline receptors. They are thus able to be used in the treatment of pathologies associated with disturbances in the functioning of those receptors, such as cardio-vascular diseases and arterial hypertension, diabetes, obesity, and psychiatric and neurological disorders, such as depression, Parkinson's disease, anorexia, Alzheimer's disease, etc..
The compounds of the invention are especially useful in the treatment of cardiovascular diseases and arterial hypertension.